1. Field of the Invention
The invention relates generally to media storage devices, and more specifically to devices, systems and methods of aligning media cartridges with rotatable reels within tape drives.
2. Description of the Related Art
Magnetic tape cartridges have been used to conveniently and efficiently store and handle magnetic recording media for tape drives. One type of tape cartridge consists of a substantially rectangular exterior cartridge housing and a single cartridge reel containing a magnetic tape positioned within the housing. The cartridge housing includes an upper housing section and a lower housing section that substantially enclose the magnetic tape, which includes a cartridge leader. The cartridge leader becomes exposed through an opening in the cartridge housing during insertion of the cartridge into the tape drive. The tape drive is then able to engage and retrieve the tape from the cartridge for recording and/or playback.
The cartridge reel may include a hub, one or more flanges, and a plurality of teeth (cartridge reel gear teeth) that are exposed through an access opening in the lower housing section. A reel driver may include a drive clutch for engaging these cartridge reel gear teeth to rotate the cartridge reel. Typically, a spring within the cartridge housing biases the reel toward the lower housing section. If the gears (e.g., teeth) on the reel driver properly engage the gears (e.g., teeth) on the cartridge reel, the tape drive may exert a force against the reel, urging the reel toward the upper housing section, thereby partially compressing the spring to promote a secure engagement between the reel driver (e.g., drive clutch) and the reel. The tape drive may then rotate the reel and guide the tape across a data transducer that reads data from and/or writes data to the tape. The cartridge reel can move at least somewhat radially (e.g., perpendicular to the rotational axis of the cartridge reel) within the cartridge housing, to allow for drive tolerances (e.g., variations in drive and/or cartridges).
While some radial movement may be desirable, radial movement may become problematic when mating the cartridge reel with a drive. Typically, during normal operation in a tape drive, cartridge reel gear teeth mate with reel driver gear teeth on the drive clutch region of the reel driver. If the cartridge reel and reel driver centerlines are not axially aligned, the gears will have difficulty mating. This may result in slipping or miscoupling, commonly referred to as “whir,” due to the sound the gears make when not engaged.
Miscoupling due to radial misalignment prevents the proper functioning of the cartridge. Miscoupling is common enough that most commercially available drives are designed to detect when gears are not properly mated, and to conduct a retry. Furthermore, miscoupling may damage the cartridge or drive gears, and may generate debris that may further interfere with cartridge function.
Centering the cartridge reel with a reel driver within a tape drive may be made even more difficult when a cartridge is placed on its end, so that the tape reel axis is parallel to the ground (e.g., the tape reel is “upright” rather than “flat”), because the cartridge reel may be shifted radially (e.g., perpendicular to the axis of rotation) by gravity. Thus, devices such as cartridge storage libraries, automatic tape cartridge loading devices, and robotic cartridge handlers may exacerbate the problem of miscoupling by shifting the cartridge reel within a tape cartridge housing.
Accordingly, the need exists to provide cartridge reels, a tape drives, and centering systems that reduce or eliminate radial miscoupling. Further, the need exists to provide a cost-effective, efficient method of centering a media cartridge and tape drive that promotes increased accuracy in coupling the tape cartridge and drive.